Sex Differences in Fasting Glucose Levels among Non-diabetic Japanese: Men Exhibit Higher Levels Than Women

Objective Sex differences in fasting glucose levels or the prevalence of impaired fasting glucose (IFG) have been observed in various populations and ethnic groups, suggesting potential variations in the pathophysiology of diabetes between men and women. However, limited research has focused on sex disparities in fasting glucose levels among non-diabetic Asian populations. This cross-sectional study investigated sex differences in fasting glucose levels among non-diabetic Japanese individuals who underwent the 75-g oral glucose tolerance test (OGTT). Methods The population analyzed comprised 176 men and 185 women, all of whom were Japanese without diabetes. Individuals with diseases or medications that affect glucose metabolism were excluded from the study. Fasting glucose and insulin levels were measured after a 12-h fast and during a 75-g OGTT. Subcutaneous and intra-abdominal fat areas were assessed using computed tomography. A multiple linear regression analysis was used to evaluate the association between sex and fasting glucose levels after adjusting for potential confounders. Results There were significantly more isolated IFG in men than in women, and men had significantly higher fasting glucose levels than women. The association between sex and fasting glucose remained significant, even after adjusting for the age, BMI, intra-abdominal fat area, subcutaneous fat area, intra-abdominal fat area/subcutaneous fat area ratio, insulinogenic index, homeostasis model assessment for insulin resistance (HOMA-IR), and 2-h glucose. Conclusion Among non-diabetic Japanese, the fasting glucose level was statistically significantly higher in men than in women, suggesting potential sex-specific variations in glucose metabolism. This sex difference was independent of the fat distribution, insulin secretion, and insulin sensitivity.